Your decision to make liquid inputs without markings is confusing, because in the game all buildings with pipes have markings for connecting liquid, not for supplying materials, it seems to me that it would be worth changing this function to how it works in the game. Until I read the description, I could not understand why the pipes do not connect to the furnace, because I am used to how it all works in the game.

Alt mode works for the fluid ingredient inputs but not the fuel inputs. I had to make a choice and that seemed best overall. The model doesn't work perfectly since it isn't optimized for this building setup but I'll do some experimentation with the 2.0 model when I get a chance.